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the use of the left hand preferentially. As a rule, lefthandedness is caused by the nature of the central nervous system, specifically the location of certain nerve centers. It may be a congenital (sometimes hereditary) or forced (as a result of disturbance of the function of the right hand) condition. There is overt and latent lefthandedness. A latent lefthander is a person who was born lefthanded but was trained to use the right hand predominantly.
When walking a straight line with eyes closed, lefthanders deviate to the right, and righthanders to the left. Some lefthanders write in mirror writing: from right to left with the left hand, from left to right with the right hand, or sometimes along the vertical. Lefthanders have two speech centers. When a hemorrhage occurs in one of them, the disrupted function is compensated for more quickly than in righthanders.
Although retraining through work and physical exercises develops both sides of the body to any desired degree, the left side remains dominant in a lefthander. Forced retraining of children is not recommended; it often leads to stuttering, strabismus, and other conditions. Upbraiding a child with lefthandedness may lead to emotional problems and nervousness. Lefthanded children do not lag behind righthanders in physical and mental development. It is necessary to take lefthandedness into consideration when selecting persons for work in which equipment is designed for operation with the right hand. In some countries, for example, Great Britain and Japan, production equipment is manufactured especially for lefthanders.